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Gold Member Username: 54danny54Betsy layne, Kentucky.. USA duh Post Number: 1416 Registered: Nov-04 | In transmission line enclosures...does the angle of the peices inside matter at all? |
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Gold Member Username: James1115Wilton, Ct Post Number: 4499 Registered: Dec-04 | "The origin of a transmission line (TL) has roots tracing back to the Stromberg-Carlson acoustic labyrinth, circa 1930. This labyrinth consisted of a long pipe, with the driver mounted at one end while the other end remained open, with a cross-sectional area about the same as that of the driver. In the early 1960's, Dr. AR Bailey experimented with different damping materials and techniques using the same basic concept in these folded labyrinth lines. His work has since become the standard for TL designs. In 1976, AT Bradbury used Dr. AR Bailey's density criteria of 0.5 lb/ft and published his paper describing changes in the speed of sound for different types of damping material such as fiberglass and long fiber wool. So, what is a transmission line? As the name implies, a transmission line is a long chamber that expends from the back of the loudspeaker. At the opposite end of this line is a vent or opening (generally the size of the driver diaphragm) to the outside of the cabinet. Properly built TL's eliminate the phase cancellation of the driver in any form and make for a nearly perfect sub system. However, TL's are seldom found in car audio because of their size and complexity. The design of a TL enclosure consists of a taper in the line, making it is possible to eliminate standing waves and resonance common to other speaker enclosures. Eliminating standing waves also protects the driver from harmful back waves that cause distortion and cone breakup. The length of the line does not allow time for air to travel through the chamber and cancel the front-wave. Because of its length, a tuned chamber, much like an open-ended pipe from a pipe organ, is created. This causes a phase shift. It is this phase shift to the rear sound wave (of the woofer) that reinforces the front-wave at the frequencies where the front-wave begins to decrease due to increased air resistance at lower frequencies, very much like a vented enclosure. The damping of a TL is unlike the "air" spring of a sealed enclosure where the cone has to fight for motion. As a result, the efficiency is better than bass-reflex enclosures, the accuracy is better than acoustic suspension, and the frequency response and linearity is better than all systems. Designing a transmission line enclosures requires thorough specifications and careful tuning. Suitable drivers for TL's usually have low QTS (0.2 to 0.4), low QES (0.3 to 0.4) and low Fs values. The distance the rear sound wave (of a subwoofer) travels in the enclosure is very specific. Determining the length is based a fraction of the wavelength of the woofers resonant frequency. For example, if the resonate frequency of the woofer used in a TL is 40 Hz, the wavelength of the frequency would be approx. 339 inches (see March 2002 issue, Box Basics II, for formula to determine wavelength). The channel inside the transmission line enclosure must be 1/4, 1/2 or 3/4 of this wavelength, resulting in a channel length of 84.75, 113 and 169.5 inches respectively. Because of the length of the channel, it is often common for a TL to be folded into a labyrinth, making it more compact. If stuffed properly with damping material such as wool, the actual length can decrease due to the resistive effect of the material on the air. Both passive radiator and transmission line enclosures may not be completely suitable for the automotive industry, but they are great alternatives to the common enclosure." Give them a try- you may be pleasantly surprised. Hopes this helps you out! |
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Bronze Member Username: Redbone15367Mo U.S.A. Post Number: 67 Registered: Sep-05 | where could i find out more? thanks |
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Gold Member Username: James1115Wilton, Ct Post Number: 4506 Registered: Dec-04 | http://www.the12volt.com/caraudio/boxes.asp |
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Gold Member Username: 54danny54Betsy layne, Kentucky.. USA duh Post Number: 1420 Registered: Nov-04 | http://www.t-linespeakers.org/projects/tlB/index.html http://www.t-linespeakers.org/ http://euridice.tue.nl/~dznamens/hobbies/Hi-Fi/Hi-Fi.htm |
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Gold Member Username: 54danny54Betsy layne, Kentucky.. USA duh Post Number: 1421 Registered: Nov-04 | i learned stuff from it... but the question remains...in the folded TL enclosure, does teh angles of the slots really matter? or wat? i came up with a conclusion that how its angled, it tapers, and that large volume of air going through the tapered end has sorta wat i liek 2 call a "jet-effect(lol)" and has more forcefor better output...this ture? |
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Gold Member Username: 54danny54Betsy layne, Kentucky.. USA duh Post Number: 1423 Registered: Nov-04 | james...mind if i message u on aim real quick |
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Silver Member Username: Koz1031Monticello, In United states Post Number: 411 Registered: Jul-04 | I am not positive on this but I believe the angles don't really matter. They are angled to help eliminate standing waves. Sean and I have talked about this b4 and if I remember, this is what it's all about. Elimination of standing waves. |
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Gold Member Username: 54danny54Betsy layne, Kentucky.. USA duh Post Number: 1441 Registered: Nov-04 | yea me and sean ws thinking bout these enclosures |